1. Field of the Invention
The present invention relates to a coordinate input/detection device optically detecting coordinates pointed by a finger or a pointing instrument such as a pen for inputting information or selecting the information. Additionally, the present invention relates to an electronic blackboard utilizing the coordinate input/detection device, and a recording medium storing a program readable by a computer and installed in the computer to control the coordinate input/detection device. Furthermore, the present invention relates to a light-receiving device applied to the coordinate input/detection device for detecting the coordinates and a method of detecting an installation position of the light-receiving device in the coordinate input/detection device.
2. Description of the Related Art
There has been an electronic blackboard that can read handwriting information written by use of a writing implement on a writing surface such as a whiteboard or a sheet of paper by an exclusive scanner, and can print the handwriting information on a recording sheet by an exclusive printer. Additionally, an electronic blackboard system has been provided recently, the electronic blackboard system including a coordinate input/detection device on a writing surface of an electronic blackboard, thereby enabling input of handwriting information written on the writing surface to a computer such as a personal computer in real time. Such an electronic blackboard system is, for example, the Soft Board manufactured by Microfield Graphics, Inc. Additionally, an application of the electronic blackboard system has led to production of an electronic blackboard system including a display device as a writing surface recently. For example, the Smart 2000 manufactured by SMART Technologies, Inc is one of electronic blackboard systems including a display device as a writing surface. The electronic blackboard system including the display device as the writing surface has an advantage of displaying handwriting information on a top of an image displayed on the display device as an overwritten image, and thus has been used in wide areas such as business and educational scenes including a meeting and a presentation, obtaining high evaluation for its effectiveness. Additionally, the electronic blackboard system may be used as an electronic conference system by including a communication function transmitting such as images and sounds, and by connecting remote places with each other by use of communication lines.
Various types of coordinate detection methods have been in practical use or have been suggested for the coordinate input/detection devices used in the above-described electronic blackboard systems. For example, one of the methods detects an electric change by use of static or electromagnetic induction when a user pushes a coordinate inputting surface by using a pen, or when the pen approaches the coordinate inputting surface. Additionally, Japanese Laid-Open Patent Application No. 61-239322 discloses a touch-panel coordinate input/detection device utilizing an ultrasonic wave as a coordinate detection method. To be concrete, the touch-panel coordinate input/detection device outputs a surface acoustic wave onto a panel, and determines a point on the panel touched by a user by detecting the surface acoustic wave weakened by the user touching the point. However, the touch-panel coordinate input/detection device must include a touch panel as a physical coordinate inputting surface for obtaining handwriting information. Compared to the touch-panel coordinate input/detection device, a coordinate input/detection device by which a user can input handwriting information without preparing a physical coordinate inputting surface, for instance, an optical coordinate input/detection device, is more appropriate for increasing a usability of an electronic blackboard system.
The optical coordinate input/detection device has been provided with various methods of detecting coordinates. For instance, Japanese Laid-Open Patent Application No. 8-240407 discloses a method of detecting coordinates by use of two optical units, each optical unit including infrared CCD (Charge Coupled Device) cameras, and an infrared LED (Light Emitting Diode) that is attached to a pointing instrument inserted to a coordinate input area. Additionally, Japanese Laid-Open Patent Application No. 9-319501 discloses a method of detecting coordinates by inserting a pointing instrument including a corner cube reflector as a retro reflector to a coordinate input area, in which laser beams are scanned by two optical units, and by detecting a position of the pointing instrument based on a reflected light from the corner cube reflector of the pointing instrument.
On the other hand, the applicant of the Japanese patent application corresponding to this US application suggests a method of detecting coordinates by providing a retro reflector around a coordinate input area in Japanese Priority Application No. 12-105671. An optical coordinate input/detection device disclosed by such as the Japanese Priority Application No. 12-105671 emits light in a fan shape from a light source provided in each of two optical units to the coordinate input area, reflects back the light emitted to the coordinate input area by the retro reflector provided around the coordinate input area, and detects the light reflected back by the retro reflector by using a photo detector such as a CCD array. In a case in which a pointing instrument such as a finger or a pen is in inserted to the coordinate input area, the photo detector does not receive only light corresponding to a position to which the pointing instrument is inserted since the light is blocked by the pointing instrument. Thus, the optical coordinate input/detection device can detect coordinates of the position to which the pointing instrument is inserted based on an output distribution of the photo detector provided in each of the two optical units. Accordingly, the optical coordinate input/detection device disclosed by such as the Japanese Priority Application No. 12-105671 can detect coordinates with a comparatively simple device structure.
Optical coordinate input/detection devices detecting coordinates by providing a retro reflector around a coordinate input area and by using two optical units includes two types of devices, which are an optical coordinate input/detection device including the optical units in predetermined positions, and an optical coordinate input/detection device in which a user can alter the optical units in a structure provided with a writing surface as the need arises. The latter optical coordinate input/detection device can be configured, for instance, by installing the optical units on the writing surface such as a whiteboard. In such a case, the user uses the latter optical coordinate input/detection device by connecting a harness that is provided in an optical unit and is used for a power supply and a communication, to a controller, and by connecting the controller to a personal computer, for instance. Additionally, in the optical coordinate input/detection device fixing positions of the optical units optionally, a position of each optical unit to be placed on the writing surface and a position of the harness of each optical unit to be connected with the controller are interrelated. For example, in a case of using the optical coordinate input/detection device by providing the optical units on a bottom left and right areas of the writing surface, the controller and the personal computer must correctly distinguish signals supplied from an optical unit located on the left area and from an optical unit located on the right area. If the controller or the personal computer mistakenly distinguishes the signals, the optical coordinate input/detection device becomes unable to detect coordinates correctly. Thus, the user must connect the harness supplied from the optical unit located on the left area and the harness supplied from the optical unit located on the right area respectively with a left input terminal and with a right input terminal of the controller.
In fact, even in the optical coordinate input/detection device including the optical units in predetermined positions, a manufacturer needs to install the optical units in the predetermined positions, and to connect their harnesses to the corresponding input terminals of the controller properly during a production and assembly process. In terms of installing the optical units and connecting their harnesses properly to the corresponding input terminals of the controller, there are no differences between the optical coordinate input/detection device including the optical units in the predetermined positions and the optical coordinate input/detection device in which a user can alter the optical units in a structure provided with a writing surface as the need arises. Accordingly, it is necessary to show a relation between a position to install each optical unit and a position to connect the harness of each optical unit with the controller at each optical unit and its harness. For example, the optical coordinate input/detection device providing the optical units in the left and right areas of a writing surface must show a difference between the harness of the left optical unit and the harness of the right optical unit visually by forming connectors of the harnesses differently or by coloring the harnesses differently, or must show a difference between the left optical unit and the right optical unit visually. Therefore, the optical coordinate input/detection device needs to include two visually different optical units despite the fact that structures and functions of the optical units are the same. Consequently, a variety of inconveniences such as complication of production and assembly, and an increase in costs related to parts and production arise in the optical coordinate input/detection device.
Additionally, even if the relation between the position to install each optical unit and the position to connect the harness of each optical unit with the controller is visually indicated at each optical unit and its harness, an operability of the optical coordinate input/detection device is low since a connection of each optical unit with the controller must be appropriately executed. Such a low operability of the device decreases production/assembly efficiency of the optical coordinate input/detection device including the optical units in the predetermined positions, at a manufacturer""s side, and burdens a user using the optical coordinate input/detection device in which the user can alter the optical units in a structure provided with a writing surface as the need arises.
Additionally, the above-described optical coordinate input/detection devices need to recognize in advance whether the coordinate input area in which the optical units are installed has a length-side ratio higher or lower than one. For instance, in a case in which an optical coordinate input/detection device installing the optical units on a whiteboard having the length-side ratio higher than one incorrectly recognizes that the whiteboard has the length-side ratio lower than one, the optical coordinate input/detection device becomes unable to detect coordinates properly on the whiteboard. Such a problem rarely arises in a device such as an electronic blackboard system including a built-in optical coordinate input/detection device, since the device recognizes the length-side ratio of a writing surface in advance. On the other hand, the length-side ratio of such as the whiteboard is previously unknown in an optical coordinate input/detection device in which a user can attach or remove the optical units on such as the whiteboard freely, and thus the above-described problem possibly arises often in the device. In addition, an optical coordinate input/detection device includes large problems especially in a case in which the optical coordinate input/detection device is applied to such as a whiteboard possible to change its length-side ratio by rotating its surface at an angle of ninety degrees.
Accordingly, it is a general object of the present invention to provide a method of utilizing only a single type of a light-receiving unit that is used as a pair in a coordinate input/detection device, and to simplify an operation to connect a harness of the light-receiving unit to a controller or the like, by which the disadvantages described above are eliminated. More particular object of the present invention is to provide a coordinate input/detection device capable of determining a correct installation position of a light-receiving unit provided therein.
The above-described object of the present invention is achieved by a coordinate input/detection device provided with a coordinate input area, including a plurality of retro reflectors provided around the coordinate input area; a first light-emitting unit; a second light-emitting unit; a first light-receiving unit that corresponds to a first position, and is installed at one of first and second positions, at which the first light-receiving unit receives light emitted from the first light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors; a second light-receiving unit that corresponds to the second position, and is installed at the other position among the first and second positions, at which the second light-receiving unit receives the light emitted from the second light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors; and a position recognition unit recognizing whether each of the first and second light-receiving units is installed at the first position or the second position, based on an output signal of each of the first and second light-receiving units.
Output signals of the first and second light-receiving units include information for determining whether each of the first and second light-receiving units is installed at the first position or the second position, in a case in which each of the first and second light-emitting units emits the light to a retro reflector located on a longer side of the coordinate input area and a retro reflector located on a shorter side thereof, and each of the first and second light-receiving units receives the light reflected by the retro reflectors, the retro reflectors being adjacent to each other. Such information includes, for instance, a shape of an output waveform of the first or second light-receiving unit, the output waveform corresponding to a space between the retro reflectors, or a ratio of lengths of output waveforms of the first and second light-receiving units, the output waveforms corresponding to the retro reflector located on the longer side of the coordinate input area and the retro reflector located on the shorter side thereof respectively. Thus, the position recognition unit can recognize the installation positions of the first and second light-receiving units by use of the information, thereby determining whether harnesses of the first and second light-receiving units are correctly connected to such as a controller for the first and second light-receiving units. Additionally, only a single type of a light-receiving unit is necessary to be used as the first and second light-receiving units since the coordinate input/detection device can detect misconnections of the first and second light-receiving units.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.